Hoisting machine



Aug. 15, 1933. I R Q 5 1,922,635

HOIST-ING MACHINE Filed June 20, 1929 g/ as 35 L9 37 INVENTOR.

ATTORNEY Patented Aug. 15, 1933 i l 1 922 635 UNITED STATES PATENTOFFICE HOISTING MACHINE Robert 0. Post, Englewood, N. J., assignor toPost & McCord, a Corporation of New York Application June 20, 1929.Serial No. 372,290

11 Claims. (01. 18S82) My invention relates to improvements in hoist-Another object of my invention is to provide ing machines of the type inwhichloads may a safety brake which is normally held in operbe raisedand lowered by winding and unwindative position but is thrown out ofengagement ing a cable on a hoisting drum. with the drum only when theservice brake is in Usually such machines are operated by an controllingposition.

electric motor or other prime mover which Another object is to provide asafety brake drives the drum in hoisting direction through of a typewhich when in operative position will the medium of a clutch. Whenlowering a load permit rotation of the drum in hoisting direction theclutch is thrown out and rotation of the but will permit rotation of thedrum in reverse or drum is controlled by means of a service brakeowering direction. acting thereon. Usually the service brake is Anotherobject of the invention is to provide operated by a foot pedal undercontrol of the a safety brake which is maintained in inoperoperator. Theclutch is normally disconnected ative position by power means, so thatin case and must be held manually in operating or enof failure of thepower, the safety brake will gaging position, the purpose of this beingto automatically be thrown into engagement to stop permit of moreaccurate control of the load. the drum a st eV 0 unwinding a- Thus theoperator may let the clutch slip slightly tion. so as to ease up theload to a desired point. To Another object of the invention is toprovide hold the load at any fixed point, the winding a safety brake ofthe character described above,

20 drum is usually provided with ratchet teeth Wi a auxi iary manualControl, whereby the adapted to be engaged by a pawl which can readbrakemay be disconnected from power so that ily be thrown into engagingposition by the it will. move automatically into operative en operator.To prevent the motor from running gagementwith the winding drum. inreverse direction an automatic brake is prot e Objects and advantages ofy invention 25 vided on the rotor shaft which is effective only willappear in the following description of a against reverse rotation of themotor. Thus if Preferred embodiment and thereafter the 110V- for anyreason power should fail while raising e ty' and Scope of the inventionWill be pointed a load, the automatic brake will prevent the load out inthe Claims. from falling so long as the operator holds the In the aeee py w 30 clutch lever in engagement. This gives the oper- Figure 1 is aview inside elevation of a single ator time to throw the pawl intoengagement with d u hoisting machine provided With y the ratchet.Furthermore, the operator could D OV d Sa y brake, Certain 1301110115 0fthe stop the rotation of the drum by depressing the chine being removedto reveal features of the pedal and thus applying the service brake.invention;

35 However, the hoisting drum is normally free Fig. 2 is a'plan view ofthe hoisting machine,

and neither the motor brake nor the service and brake will come intoplay automatically to stop .Figs. 3 to 5 are detail views of parts ofthe the drum; for the motor brake although autosafety" brake mechanism,showing one of the matically stopping the motor will not stop the safetybrake shoes in three different positions.

40 drum unless the clutch is held in engaging posi- As shown in theaccompanying drawing, the, tion and the service brake is inactive unlessthe hoisting machine is provided with a base 10 on pedal is depressed.An operator might be sudwhich are mounted two brackets 11.Thesebrackdenly stricken, releasing the clutch lever and the ets providebearings for the rotor shaft 12 of a pedal, and then there would benothing to premotor 13. The shaft 12 is provided with a i 45 vent theload from falling. There is also a servo-brake consisting of abrakewheel 14 which possibility that an operator might become exis adapted tobe engagedby brake shoes 15 and cited or confused, releasing the clutchand de- 16 supported on a yoke 1'7. The latter is mountlaying depressionof the pedal until the load ed to oscillate on a stud supported in abracket had gathered sufficient momentum to break the 18 secured to thebase 10. The shoe 16 is di- 50 hoisting cable or wreck the machine. 7rectly connected to one arm of the yoke, while 'It is an object of myinvention to overcome the shoe 15 is connected to the other arm of suchdangers by providing an automatic safety the yoke by means of a link19.. When the brake which will automatically come. into play motorshaftturns in normal direction, as shown to prevent uncontrolled dropping orlowering of by the arrow in Fig. 1, the brake is ineffective 5 the load.and the shoe l5 merely trails along the brakewheel 14, because the pointof attachment of the shoe 15 to the link 19 is above a line passingthrough the shaft 12 and the point of attachment of link 19 to the yoke.However, should the rotor be turned in the opposite direction, the shoe15 would be dragged downward by the brake wheel 14, causing the yoke 17to oscillate and force the opposite shoe 16 also into operativeengagement with the brake wheel.

The brackets 11 also provide bearings for a shaft 20 on which is mounteda cable drum 21. The shaft 20 is driven by the motor 13 through a trainof gears 22 so as to turn in the direction of the arrow in Fig. 1. Thecable drum 21 is connected to the shaft through a friction clutch 23 andthis clutch is operated by means of a lever 24. The construction of thefriction clutch may be of standard type and is not shown in detail inthe drawing. The clutch is normally spring-pressed in disengagedposition but may be moved into andheld in engaging position by operatinga clutch, lever 24.

The hoisting drum 21 is controlled by a service brake when lowering aload and to this endthe drum is formed at one end Witha brake surface 25adapted to be engaged by a brake band 26. This band is anchored at oneend to a bracket 2'7, while the free end of the band is secured to anarm 28 fixed upon a shaft 29.

- lever normally in the position indicated by broken lines at A inFig. 1. The hoisting drum is also provided at one end with ratchet teeth31 adapted to be engaged by a pawl 32; The pawl may be thrown by handinto or out of engagement with the ratchet teeth.

" The ratchet teeth are so formed as to prevent reverse rotation of thedrum when engaged by the pawl, but will throw the pawl out of engagementwhen the drum is driven by the motor 1 to raise the load.

Secured to the drum near the forward side of the machine is a safetybrake-wheel 33'. .This

is adapted to be engaged by a pair of brake shoes 34 and 35 carried by ayoke 36 pivotally mountedon the adjacent bracket 11. The brake shoe 34is directly connected to one arm of the yoke 36 while the other brakeshoe 35 is connected to the other arm of the yoke by means of an arm 37.This construction, it will be observed, is similar to that of the brakeon the motor shaft with this difference, however, thatposition shown inFig. 3. is formed with a rearward projection 35a which is urged by aspring 41 against a stop 37a formed on the arm 37. When the drum isdriven in ii hoisting direction the parts will assume the po-' sitionshown in Fig. 3 with the upper edge of the shoe 35 engaging and trailingon the brake wheel 33. When the direction of rotation of the drum isreversed the shoe 35 will be dragged flown to the position shown in Fig.4, thereby rocking the yoke 36 on its pivot and forcing the Thearrangement is such that.

However, when the solenoid is deenergized the arm will drop by gravityto the The brake shoe 35 shoe 34 also into engagement with the wheel 33.The latter is thus arrested. When the solenoid is energized the arm 37is lifted, raising the shoe 35 clear of the wheel 33 and a compressionspring 36a acting on one arm of the yoke 36 restores the latter to theposition shown in .Fig. 1, with the other arm of the yoke bearingagainst a stop 362). In this position the shoe 34 is withdrawn fromengagement with the wheel 33.

On one side of the bed of the machine, I have provided a control box 42with a controller handle 43 by which current to the motor may becontrolled. Current is fed into the control box through a pair of mains44 and 44a, respectively.

, Tapped across these mains are a pair of leads 45 and 46, respectively,of which the lead 45 runs directly to one terminus of the solenoid,while the lead 46 runs to a contact brush 47 carried by the pedal 30.This'contact brush is adapted to engage a contact plate 48 which isconnected by a line 49 to the other terminus of the solenoid 40. Whenthe pedal is in its normal raised position A, the brush will bedisconnected from the contact plate 48 and the solenoid will bedeenergized and the safety brake will drop by gravity into a position tooperate. When the pedal 30 is lowered to the operating position shown byfull lines in Fig. 1, the circuit will be closed through the brush 4'?and plate 48 to the solenoid 40, and the brake shoe 35 will be raisedout of operative engagement with the brake wheel 33, as in Fig. 5.

Thereafter further depression of the pedal 3Q down to the limit of itsbraking stroke (indicated by broken lines B, in Fig. 1) will maintainthe electrical connection to the solenoid, so that the safety brake willcontinue to be held inoperative as long as the pedal is inoperativeposition. To permit throwing out the safety brake by hand, even shouldpedal 36 be depressed, a hand switch 50 is provided in the lead 46.

An electric lamp 551 is bridged across the mains 44, 44a, so that theoperator will know at any time whether current is available to operatethe motor or safety brake; for in case of any failure in current, due totheblowing of the fuse or for any other reason, the lamp 51 will beextinguished.

The operation of the machine is as follows: To raise a load, theoperator throws in the clutch lever 24 and operates the controllerhandle 43 to energize the motor 13. This turns the drum in the directionof the arrow in Fig. 1 and although gravity is drawing the arm 37downward there will be no braking action of the safety brake because ofthe direction in which the drum and brake wheel are rotating. Whenlowering a load, the operator, having'thrown the control handle 43 tocut off current from the motor, depresses the pedal 30 to apply theservice brake. Then the pawl 32 is thrown out of engagement with ratchetwheel 31, the-clutch lever 24 is released and the load is lowered in theusual manner, under control of the service brake. The, instant the pedalis depressed to the position shown by full lines in Fig. 1 the brush 47engages contact plate 48 energizing solenoid 40, which raises the arm 37and holds the safety brake in inoperative position. If, for any reason,the operator should remove his foot from the pedal 30, re-

leasing the service brake, the pedal would spring,

up to the position A, under action of spring 300:. deenergizing thesolenoid and permitting the brake shoe 35 to drop to operativeengagement with the safety brake wheel 33. Thereupon the iii) safetybrakewould act to arrest the hoisting drum and prevent the loadfromdropping. The same thing would occur even if the operator werelowering the load under control of the service brake 26, should thecurrent fail, because as soon as the solenoid is deenergized the safetybrake will drop into operative position. The hand switch 50 could alsobe operated to deenergize the solenoid and throw in the safety brake.Thus, my invention provides against any emergency which might arise andrenders the operation of the cable hoist safe at all times'and under allconditions.

I have shown my invention as applied to a single-drum hoisting machine,but it will be obvious that the same mechanism can be aplied to amultiple-drum hoisting machine; in other words, a safety brake would beused with each drum and would cooperate with the pedal of the normalservice brake of said drum in the manner described above.

While I have shown a specific embodiment of my invention, I wish it to,he clearly understood that I do not limit myself to the particular typeof brake or other mechanism illustrated, but reserve the right to makesuch changes in details of construction and in form and arrangement ofparts as fall within the spirit and scope of the following claims.

I claim:

1. In a hoisting machine, the combination with a hoisting drum, of aservice brake, means for operating the service brake to control andarrest rotation of the drum, a safety friction brake normally operatingto arrest rotation of the drum, and means for rendering the safety brakeinoperative when the service brake is operated.

2. In a hoisting machine, the combination with a hoisting drum, of aservice bralre, means for operating the service brake to control andarrest rotation of the drum in one direction, a safety friction brakenormally acting to arrest rotation of the drum in said direction, andmeans controlled by the first-named means for rendering the safety brakeinoperative when the service brake is operated.

3. In a hoisting machine, the combination with a hoisting drum, of aservice brake, a lever for operating the brake to control rotation ofthe drum, a safety friction brake normally in position to arrestrotation of the drum, and means controlled by said lever for withdrawingthe safety brake from operative position while the service brake is incontrolling position.

4. In a hoisting machine, the combination with a hoisting drum, of aservice brake, a pedal for operating the brake to control rotation ofthe drum, a safety friction brake normally in position to'arrestrotation of the drum, and means controlled by said pedal for withdrawingthe safety brake from operative position while the service brake is incontrolling position.

5. In a hoisting machine, the combination with a hoisting drum, of aservice brake, a pedal for operating the bralre to control rotation ofthe drum, a safety friction brake normally in operative position toarrest rotation of the drum, pow er energized means for holding thesafety brake in inoperative position, and a control device actuated bysaid pedal for energizing said means to release the safety brake whilethe pedal is operated to control the service brake.

6. In a hoisting machine, the combination with a hoisting drum, of aservice brake, a pedal for operating the brake to control rotation ofthe drum, a safety brake normally in operative position to arrestrotation of the drum, electrically energized means for holding thesafety brake in inoperative position, a switch in the circuit of saidmeans and controlled by said pedal for energizing said means while thepedal is in position to control the service brake.

7. In a hoisting machine, the combination with a hoisting drum, of aservice brake, a pedal for operating the brake to control rotation ofthe drum, a safety brake normally in operative position to arrestrotation of the drum, electrically energized means for holding thesafety brake in inoperative position, a switch in the circuit of saidmeans and controlled by said pedal for energizing said means While thepedal is in position to control the service brake, and a hand switchalso in said circuit.

8. In a hoisting machine, the combination with a hoisting drum, of aservice brake, a pedal for operating the brake to control rotation ofthe drum, a safety brake normally in operative position to arrestrotation of the drum, electrically energized means for holding thesafety brake in inoperative position, a switch in the circuit of saidmeans and controlled by said pedal to close said circuit while the pedalis in position to control the service brake, a pair of power lines supplying current to said circuit and a lamp bridged across said powerlines.

9. I In a hoisting machine, the combination with a hoisting drum,driving means for rotating the drum in hoisting direction, and means fordisconnecting the drum, of a service brake, means for operating the sameto control rotation of the drum in reverse direction, means normallyholding the safety brake in operative position, said safety brake whenin operative position permitting rotation of the drum in hoistingdirection and arresting rotation of the drum in reverse direction, andpower actuated means for withdrawing the safety brake from saidoperative position while the service brake is in controlling position.

10. In a hoisting machine the combination with a hoisting drum and amotor for driving the drum and a source of power for energizing saidmotor, of a safety brake for controlling rotation of the hoisting drum,restraining means energized from said source of power for holding thesafety brake inactive, a service brake movable into position to controlrotation of the drum, and

means for disconnecting the restraining means from said power sourcewhen the service brake is in controlling position.

11. In a hoisting machine, the combination with a hoisting drum, of aservice brake, means for operating the service brake to control andarrest rotation of the drum, a safety brake normally operating toarrestrotation of the drum,

means interconnecting the brakes whereby when the service brake isoperated the safety brake will be inoperative, and manually controlledmeans for restoring the safety brake to operative condition while theservice brake is in operation.

ROBERT C. POST.

